Water closet cabin

Abstract

A self-contained water closet cabin having a renewable energy generator e.g. solar panel 301, for charging an electrical energy store e.g. 12V DC batteries 303, a toilet, an air heater 305 located within a first proximity of the toilet and a controller 304 configured to control operation of the heater having a control signal input means suitable for activating the heater when an occupant of the cabin is seated on the toilet, wherein the input means include a sensor for detecting a person in a second proximity of a toilet for activating the heater only when a person is within the second proximity. The input means may further comprise a pressure sensor, or a button within a proximity of the toilet, such that the air heater is only activated or activatable during use of the toilet. The controller may automatically stop the heater, or may run the heater for a predetermined time limit. There may a be a door opening sensor. The heater may direct warm air towards the occupant’s lap instead using more energy to space heat the whole toilet cubicle.

Description

The present invention relates to a water closet cabin, particularly to a water closet cabin with heating. Background The present invention relates to water closet cabins, e.g. for use in remote locations or worksites where mains power and / or sewerage connections are unavailable. Traditionally welfare cabins are supplied with an integral generator set, i.e. a diesel engine generator, to supply off-grid power to electrical appliances within the cabin. It is a typical requirement of conventional generator sets that they are sufficiently powerful to run all of the internal appliances of the welfare cabin simultaneously. The downside of this is that running all the appliances simultaneously does not occur frequently, or for long periods, so the diesel engine of the generator set can be run close to idle for a significant portion of its operation. This type of operation represents an inefficient use of the engine, thereby incurring unwanted fuel consumption and increasing engine wear. If diesel engines are run at either low speeds or low loads, for example when a generator set is left idling as a so-called “standby” generator, or when a low load is applied to a higher-capacity generator set, then incomplete combustion of the fuel can occur, leading to carbon fouling or ‘coking’ issues. Incomplete combustion of the fuel leads to carbon formation in the engine, which is detrimental to engine efficiency and which in turn damages engine components, such as injectors, piston rings, as well as the seals that the piston rings form. As well as carbon build-up itself, coking can cause further resulting problems with engine operation. For example, as a result of the decreased sealing capacity caused by coking damage, hot combustion gases can reach, and thereby ignite, oil in the system (often indicated by the engine producing blue smoke), which reduces the amount of oil present for lubrication purposes. In addition, incomplete combustion of the fuel may cause the formation of acids in the engine oil, which may cause further damage to the engine components over time. Such issues, amongst others, increase the likelihood of engine faults and require the engine to be serviced on a regular basis, which thereby increases the maintenance costs associated with self-contained cabins. Such costs can contribute to a significant proportion of the overall costs of operating a self-contained water closet. EP 1 716 298 discloses further perceived problems with the use of diesel generators in self-contained cabins, such as noise, fuel consumption and exhaust fumes. As a solution EP 1 716 298 proposes a self-contained lavatory cabin with a solar panel to power electric lights and a burner and heat-exchanger arrangement for air heating in the cabin. The hot air can be used for heating the cabin interior, for a hot air 10 dryer and to heat water for storage in a hot water tank. Simple controls are enabled using an air temperature sensor and an infra-red sensor to detect a person within the cabin. The lights and other electrical components are activated in a stand-by mode when a person is present and air heating is initiated if the internal cabin temperature is below a threshold temperature. However, there are numerous cabin usage scenarios in which a relatively high energy consumption by the cabin is required, for example on a busy work site or at an event. In such scenarios, a solar powered cabin can fail to meet the energy demand and any onboard batteries can become drained quickly. The heating is the biggest power draw so it needs to be handled more efficiently to remove the need to burn fuel for power. It is an aim of the invention to provide a water closet cabin that mitigates one or more of the above-mentioned problems. Statements of invention According to a first aspect of the invention there is provided a self-contained water closet cabin having: a toilet, a heater located within proximity of the toilet, a controller configured to control operation of the heater, and a control signal input means for activating the heater when an occupant of the cabin is seated on the toilet. The heater is configured to be activated only when an occupant is seated on the toilet. The purpose of the heater is not to space heat the whole toilet cubicle. The purpose of the heater is to deposit warm air into the occupants lap whilst they are seated on the toilet. This method of heating significantly reduces the power consumption. The heater may comprise a fan heater. The heater may be located directly above the toilet and configured to deposit warm air downwardly towards an occupant when seated on the toilet. The control signal input means may comprise a button. The button may be located out of reach an occupant whilst standing. The button which is not easy to access unless you are sat on the toilet so should rarely be pressed when just the urinal is used or someone wants to just wash their hands. Every endeavour is being made not to run the heaters. The cabin may further comprise a proximity sensor located within proximity of the toilet and the heater may be configured to be activated by user within proximity of the toilet. The cabin may further comprise a pressure sensor located within or on the toilet and the heater may be configured to be activated by a pressure sensor located on the toilet. The heater may be on a predetermined timer. The heater may be on a 180s timer. The heater when activated by a sensor may be deactivated by the sensor. The heater may be activated by a button and deactivated by a pressure or proximity sensor. The heater may not be re-activated until the pre-determined time has passed. The cabin may further comprise an external door and an actuation sensor to sense when the external door has been opened and closed, such that the heater is configured such that it cannot be re-activated until the external door has been opened and closed. The cabin may comprise an internal wall creating a plurality of compartments each comprising a toilet. The cabin may further comprise a vent system. The vent system may comprise a chamber and a vent located within each compartment of the cabin. The vents are connected by the chamber. The vents are in fluid communication with one another by way of the chamber. The chamber may comprise a plenum chamber. Each vent may be electrically actuated. The controller may be configured to control operation of the vents. The vents may be actuated by the controller. Each compartment may comprise a temperature sensor and an occupancy sensor. The temperature and occupancy sensor may provide a control signal input means for actuating a vent. If there is an occupant in one of the compartments and the temperature is higher in a compartment with no occupant the electrically actuated vents are employed to divert heat from the compartment with the higher temperature to that compartment with a lower temperature and occupancy. Such that the warm air is only directed to the compartments that are both occupied and have a low enough temperature to demand heat. May comprise four or six toilet compartments. According to another aspect of the invention, there is provided a self-contained water closet cabin comprising: a renewable energy generator; and an electrical system having an energy store arranged to be charged by the renewable energy generator; a toilet; a heater located within proximity of the toilet; a controller configured to control operation of the heater; and a control signal input means for activating the heater when an occupant of the cabin is seated on the toilet. According to another aspect of the invention, there is provided a self-contained water closet cabin comprising: a renewable energy generator; and an electrical system having an energy store arranged to be charged by the renewable energy generator; a toilet; an air heater located within proximity of the toilet; a controller configured to control operation of the heater; and a control signal input means for activating the heater when an occupant of the cabin is seated on the toilet. According to another aspect of the invention, a free-standing water closet cabin having a water system comprising: a tank for holding water, a water heater for heating the water within the tank, a temperature sensor for measuring the temperature of the water within the tank, a controller configured to control the temperature of the, the water heater being activated by the controller once in a predetermined time period to heat the water within the water tank to at least 65°C. Heating the water to at least 65°C protects from legionella. The water heater may be an immersion heater. The water heater may be a DC, AC, or solar immersion heater. The controller may intermittently activate the water heater to a standby temperature for the remainder of the predetermined time period. The standby temperature may be determined by a user. The controller may be connected to an operating system which determines the standby temperature. The standby temperature may be determined by the current water temperature and external temperature. There may be a temperature sensor configured to detect external temperature. The temperature sensor may be located on the outside of the cabin. The operating system may be connected to a wireless network wherein it can obtain the weather forecast to determine the external temperature. The standby temperature may also be determined by the available solar power and battery SoC. The controller may intermittently activate the water heater to keep the temperature above 35°C for the remainder of the predetermined time period. According to another aspect of the invention there is provided a free-standing water closet cabin having a water system comprising: a renewable energy generator; and an electrical system having an energy store arranged to be charged by the renewable energy generator; a tank for holding water, a water heater for heating the water within the tank, a temperature sensor for measuring the temperature of the water within the tank, a controller configured to control the temperature of the, the water heater being activated by the controller once in a predetermined time period to heat the water within the water tank to at least 65°C. According to another aspect of the invention there is provided a self-contained water closet cabin comprising: a renewable energy generator; and an electrical system having an energy store arranged to be charged by the renewable energy generator; and a heater for frost protection. The cabin may further comprise a water system, the heater for heating the water system for frost prevention. The water system may comprise an opening. If there is insufficient power available to operate the heater, water from the system may be evacuated through the opening. Detailed description Practicable embodiments of the invention are described in further detail below with reference to the accompanying drawings, of which: Figure 1 shows a schematic above / plan view of a water closet cabin in accordance with an example of the invention. Figure 2 shows a schematic above / plan view of a water closet cabin in accordance with another example of the invention. Figure 3 shows a schematic block diagram illustrating a water closet electrical / control system according to an example of the present invention. The invention focuses on providing a water closet cabin with efficient methods of personnel heating and immersion heating such that the energy use for the cabin is kept to a minimum, whilst also allowing a long service interval. The cabin has been developed to give people energy efficient toilet facilities in remote areas where there is no available mains power and / or sewerage connections. A water closet (WC) cabin according to an example of the present invention is shown schematically in Figure 1 and generally designated 100. The water closet can be located anywhere it is needed without connection to water or electricity mains. The WC cabin comprises an outer wall 101 around its perimeter and a plurality of inner dividing walls 102, which separate six toilet compartments 103 and a plant room 104. The outer wall 101 provides for a rigid container that is resilient to vandalism. The outer wall 102 may comprise smooth stainless steel. In the example shown in Figure 1 there is a six toilet compartments 103. Three of the toilet compartments are intended for male occupants, and three of the toilet compartments are intended for female occupants. Any other combination of male / female toilet compartments are possible. The cabin in this example is approximately 5 metres in length. The plant room 104 comprises a freshwater tank 105 and the electrical components (not shown) for the cabin 100. The electrical components can be accessed internally through a hatch in one of the toilet interior walls. The freshwater tank 105 may comprise a 500 litre water tank. Each of the toilet compartments 103 is provided with a door that opens to the exterior of the WC cabin 100. The doors each have locks and are designed to be difficult to break into by way of their fitment into the corresponding frame in the outer wall 101, as well as by the nature of the lock. Each of the doors comprise door closers, such that they are not left open accidentally by a user. The cabin 100 in this case is mobile and comprises wheel arches 106. The wheel arches 106 are located within the plant room 104 with one at each side of the cabin 100. The cabin 100 further comprises a 2500kg axle, a tow hitch, and a standard lighting and braking system. Alternatively, the cabin may be static. The female toilet compartments each comprise a toilet 107, a sink 108 with a tap 109 to provide hot or cold water. The taps 109 fitted within each sink 108 may be non-concussive taps such that water usage is kept to a minimum. The toilets 107 may comprise micro-flush toilets. Each micro-flush toilet uses minimal amounts of water per flush to reduce the waste tank capacity required to prolong the duration between service visits to empty the tank. The male toilet compartments each additionally comprise a urinal 110. The urinal 110 in this example may comprise a waterless urinal such that it does not have a connection to a fresh water tank for cleaning / flushing. Instead, the urinal has an outlet pipe connected to a waste tank and may comprise a valve in the outlet pipe, e.g. a one-way / non-return valve that is biased to a closed condition and openable by liquid thereon. The plumbing components described above are in fluid communication with the onboard fresh water tank 105. Additionally, the cabin may also include an optional water mains connection if it is available. The plumbing components are in fluid communication with an onboard waste tank. Additionally, or alternatively, the components may be plumbed into mains sewerage if available. Electrical components within each toilet compartment comprise a light, a personnel sensor and a heater. The toilet compartments may additionally comprise a hand dryer. The personnel sensor can be provided within the light module in this example but could otherwise be provided as a separate component if desired. The personnel sensor typically comprises a proximity sensor and / or movement sensor of a known type. An additional sensor is provided in the cabin in the form of a light sensor. The light sensor senses the level of ambient light within the toilet compartment 103. In addition to the sensors described above, a door sensor could be used to detect entry / exit to the compartment. The use of the various sensors is described below with reference to the electrical system. The heater provided within each toilet compartment 103 may comprise electrical fan heater. At least one skylight may be provided in the roof so as to allow entry of ambient light into the toilet compartments. The skylight or skylights are typically formed as a panel of transparent or translucent material mounted across an opening in the cabin roof. In other examples, the skylight or skylights could be provided in the upper region of the outer wall 101 of the cabin if desired. A solar panel is mounted on the roof of the WC cabin 100. The solar panel may be mounted adjacent the skylight or between two skylights. One or more solar panel may be provided depending on the available area for mounting. There are also solar panels fitted to the sides of the outer wall 101. The solar panels are fitted to at least three of the four sides of the outer wall 101. The solar panels mounted on the roof of the WC cabin may be angled. The solar panels may be permanently fixed at an angle or movable by a user or remotely. The solar panels may be provided on a sliding tray extending from the roof to maximise the surface area of solar panels provided. One or more external light may be provided on the external side of the outer wall 102 or roof. The external light may have a proximity / movement sensor. Alternatively, the external sensor could be provided separately. Whilst the waste water tank is described as being within the equipment compartment, it could be located beneath a floor of the WC, e.g. beneath the user and / or equipment compartment. In some embodiments, the cabin is configured to collect rainwater. The cabin may comprise a rainwater harvesting system to reduce number of service visits to the cabin. The cabin may comprise a system to collect rainwater from the roof. Typically, the roof and / or solar panel is sloped or otherwise angled such that rainwater flows toward one or more collectors. The water may then be stored and / or integrated into the water system as described above (e.g. in the fresh water tank 105). The system may use a guttering / downpipe arrangement, or the collector could be integrated into the roof. The rain water may be processed to at least partially render the water safe for use (e.g. may not provide drinking water, but water suitable for washing etc.). There may be a decontamination system comprising one or more of: a filter (e.g. particulate and / or reverse osmosis); a chemical filtration / biocidal system; UV biocidal system; bacterial membrane filter; or other suitable mechanism. In some embodiments, the water may be sufficiently processed to provide potable water. Processed water may then be deposited into the water tank 105. Any excess water (i.e. water that cannot be adequately stored or processed) may be discarded. Typically, the system is configured such that excess water will overflow the collector and either collects on the roof or is discharged onto the ground. The cabin may comprise a “grey water” system. The grey water system collects water that is used by one system and uses the same water to provide for a second system. For example, water collected from one or more sinks in the cabin. The water is stored in a grey water tank. The grey water may then used to flush the toilet instead of using freshwater from the tank. The grey water tank is fitted with sensors to determine the level of water therein. If the level drops below a predetermined threshold, water from the freshwater tank is introduced into the grey water tank. Water from freshwater tank may increase until the water level reaches a “high level”. The “high level” volume is set such there is still some available capacity in the freshwater tank from future hand washing (i.e. the system ensures sufficient water remains in the freshwater tank). The grey water tank is fitted with an overflow that feeds directly into the waste tank for when there is more water collected (e.g. from handwashing) than is required (e.g. to flush the toilet for prolonged periods). All plumbing components susceptible to frost damaged are located within the confines of a heated insulated box. Each toilet compartment may comprise an electrically actuated vent. The vents may be employed to diverted heat from to an appropriate cubicle. Figure 2 shows a schematic above / plan view of a water closet cabin in accordance with another example of the invention. In this example, the WC cabin 200 comprises an outer wall 201 around its perimeter and a plurality of inner dividing walls 202, which separate four toilet compartments 203 and a plant room 204. The cabin 200 comprises the same formation as the four toilet compartments located at one end of the six toilet cabin 100. The four toilet cabin may be static having no wheel arches. The four toilet cabin 200 may comprise a smaller plant room 204 than that of a six toilet cabin 100. Save for the afore-mentioned differences, the cabin 200 shown in Figure 2 comprises the same features as the cabin 100 shown in Figure 1 and described above. The cabins 100 / 200 may comprise standard ply flooring with vinyl covering. The flooring may further comprise enhanced insulation. The interior panels of the cabins 100 / 200 may comprise foam and / or glass reinforced plastic. The plant stores 104 / 204 each house the following: - An electrical energy store, e.g. in the form of a battery or battery bank; - A fresh water tank 105 / 205; - A waste water tank; - A water pump; - A water heater; and - An electrical control system. The cabins 100 / 200 are a generator-free, burner-free cabins. All power is from renewable energy sources. Whilst the examples described herein refer to a solar panel as providing a renewable energy source, it will be appreciated that other renewable energy sources can additionally or alternatively be used, including for example a wind turbine or water wheel. Depending on the renewable power supply, additional or alternative power converter means may be implemented as would be understood by the person skilled in the art. The electrical control system comprises a controller provided as one or more processor or logic circuit in communication with the sensors described herein and arranged to output control signals to the various electrical components of the electrical system. The electrical control system may also comprise a fuse box, e.g. comprising one or more conventional fuse / trip-switch for selectively denying power to one or more electrical components, e.g. in response to an electrical fault. The control system may further comprise a set of electrical switches under the control of the controller, e.g. switches for each electrical circuit connected to the electrical system. Although the invention is described herein with examples of four and six toilet compartments, the invention is for use with a cabin with at least one toilet compartment. An overview of the electrical system 300 is shown in Figure 3. The electrical system 300 comprises a DC system / circuit. The DC system comprises a 24V system. However alternative DC voltages may be provided to suit local requirements in different countries. The system 300 comprises the following components: • Solar panel 301 • Battery charger 302 • 24V DC batteries 303 • Controller 304 • Air heater 305 • Frost protection heater 306 • Water heater 307 The electrical system does not comprise a fuel burner or a generator. The system is powered solely by renewable energy. The batteries 303 comprise 24V DC lithium ion batteries. Alternatively, any suitable battery type with any suitable batter may be used. The frost protection heater 306 may comprise a 24V microheater for frost protection. The toilet is a freshwater system with pumps, filters, taps and piping that needs protecting from frost damage. All components susceptible to frost damaged are contained under the central insulated sink pod such that they can be warmed sub zero temps (using the min amount of power) to prevent water from freezing. The six toilet cabin described in Figure 1 may comprise a 24V 6 litre immersion heater as the onboard water heater 307. In a cabin comprising fewer toilet compartments, such as that shown in Figure 2, there may be provided a smaller capacity immersion heater as the onboard water heater 307. The air heater 305 may comprise a 24V multi setting fan. There may be three different power settings and three different fan speeds the fan heater 305 operates at. The system 300 may further comprise rainwater harvesting and greywater recycling. Apparatus for rainwater harvesting and greywater recycling known in the art may be included in the system 300. The system may further comprise an inverter for external / internal socket. The solar panel 301 and batteries 303 are connected. The DC output of the solar panel 301 can thus be used to charge the batteries 303 via a battery charger 302. The battery charger 302 may comprise a charge controller, e.g. to monitor the level of charge on the battery and selectively disconnect the battery when a maximum charge level is reached. The battery charger 302 may optionally comprise a DC-to-DC converter / regulator. The batteries may additionally / alternatively be fitted with a load shedder so that if for any reason the battery charge level drops too low the load is switched off by the controller to prevent the batteries being deep discharged. This could happen e.g. overnight or when there is insufficient solar power, and no fuel for the generator to work or a generator failure. In the example of Figure 2, each of the heating appliances are controlled at least in part in accordance with the output of the one or more sensors. The controller 304 comprises a microprocessor, such as a programmable circuit board or programmable logic device. The controller 304 is preprogramed. The electrical system may comprise one or more sensor. The controller may permit or deny power to one or more electrical appliance based on the output of said one or more sensor. The sensor may comprise any or any combination of: a proximity / movement sensor, a water temperature sensor, an air temperature sensor, a light sensor, a flow sensor and / or a closure actuation sensor. The cabin comprises low power LED internal and external lighting. The lighting inside the cabin is 24V LED lighting consuming minimal power, it is controlled so that it only illuminates when there is someone present (according to the output of an occupancy sensor or a door opening sensor) and there is insufficient natural light (according to a comparison of the output of the light sensor with a minimum threshold value of ambient light). The occupancy sensor may comprise a PIR sensor. The control system may also switch off the internal light after a set time of operation to conserve energy, e.g. a period for which the presence of a person within the cabin is not detected. Natural light is provided inside through the use of the skylights described above. This eliminates the need for internal electric lighting during most daylight hours. The external lighting is 24V LED lighting consuming minimal power, it is controlled so that it only illuminates when there is someone present and there is insufficient natural light (i.e. determined according to the relevant sensor outputs in a manner akin to the internal lighting control). The control system also turns it off after a set time to conserve energy. Toilet compartment heater There is an air heater provided in each toilet compartment 103 / 203. The fan heater is located within proximity of the toilet of each toilet compartment such that air is directed towards a user when seated on the toilet. The fan heater may be located directly above the toilet and direct the heated air downwardly. Alternatively, the fan heater may be located adjacent toilet and direct the heated air sideways, for example the fan heater may be located in the sink panel beside the toilet directing heat sideways towards the toilet. The fan heater is activated by a control signal input means. The control signal input means may be activated by a button located within reach of a user seated on the toilet. The button may be located such that it is out of reach of a user when standing. Alternatively, the air heater may be activated by a proximity sensor located within the region of the seat of the toilet or a pressure sensor located on the seat of the toilet, such that it is activated when a user is seated on the toilet. The heater 305 is not configured to be activated when there is an occupant within the toilet compartment 103 / 203 but the toilet 107 is not in use. For example, the heater 305 is not configured to be activated when the sink 108 or urinal 110 is in use and the toilet 107 is not in use. The fan heater 305 is configured to only heat a user when seated on the toilet 107. The controller 304 of the electrical system 300 is arranged to receive the output signal from the button / proximity sensor / pressure sensor described above and switch on the fan heater 305. The fan heater 305 may have a pre-set duration of operation for each time it is activated. The pre-set duration of operation of the fan heater 305 may be of the order of 30s. For example, the pre-set duration may be between 30s, 60s or 120s and 180s, 240s or 300s. The pre-set duration of operation of the fan heater 305 may be 60s, 120s, 180s, 240s. The pre-set duration of operation of the fan heater 305 may be 180s. The pre-set duration of operation of the fan heater may be changed remotely. The pre-set duration of operation of the fan heater may be increased or decreased remotely. The pre-set duration may be changed from a control interface within the cabin. The control interface within the cabin may only be accessible to certain users. The control interface within the cabin may comprise a security wall such that is it only accessible to certain users, for example site managers. Alternatively, when the fan heater 305 is operational by a proximity sensor or pressure sensor and arranged to be activated when the user is seated and deactivated when the user is no longer seated. A combination of a button and proximity or pressure sensor may be user such that the user triggers the fan heater 305 for a pre-set duration by pushing the button and the heater 305 and the proximity or pressure sensor shuts the fan heater 305 off when the toilet is not longer in use and the user is no longer on or within proximity of the toilet seat. Once the heater has been activated, the heater may not be activated again until for a pre-determined duration of time. Alternatively, there may be an actuation sensor above the external door of the toilet compartment 103 / 203 and the heater may not be activated again until the sensor detects that the external door of the toilet compartment 103 / 203 has been opened and closed. This avoids abuse of the heater 305 and minimises power draw of the heater. The air heater 305 may comprise a 24V multi setting fan. There may be three different power settings and three different fan speeds the fan heater 305 operates at. The air heater 305 is used to provide comfort to the user without space heating the entire toilet compartment 103 / 203. Where the cabin comprises two or more compartments, the cabin may further comprise a vent system. The vent system may comprise a chamber and a vent located within each compartment of the cabin. The vents may be connected by the chamber. The vents are in fluid communication with one another by way of the chamber. The chamber connecting the vents in each compartment may comprise a plenum chamber. The chamber may hold air at a pressure above that within the compartments of the cabin. Each vent may be electrically actuated. The controller may be configured to control operation of the vents. The vents may be actuated by the controller. Each toilet compartment may comprise an electrically actuated vent. The vents may be employed to diverted heat from one of the toilet compartments to another toilet compartment where appropriate. There may be a temperature sensor in each of the toilet compartments 103 / 203 and an occupancy sensor in each of the toilet compartments 103 / 203. The temperature and occupancy sensors may provide a control signal input means for actuating the vents. If there is an occupant in one of the compartments and the temperature is higher in a compartment with no occupant, the electrically actuated vents are employed to divert heat from the compartment with the higher temperature to that compartment with a lower temperature and occupancy. Such that the warm air is only directed to the compartments that are both occupied and have a low enough temperature to demand heat. The fan heater of each compartment may be located within proximity of the vent of each compartment, such that the fan heater disperses the heat directed into the compartment by the vent system. If the temperature of the compartment is at above a certain temperature, the fan heater may not be activated. For example, the certain temperature may be between 15°C, 18°C, or 20°C and 25°C, 30°C, or 40°C. Water heater The water heater 307 may comprise an immersion heater. Although not shown in the figures, it will be appreciated that the water heater 307 is part of a water heating system further comprising a water tank and a temperature sensor for sensing the temperature of the water within the water tank, the temperature sensor in communication with the controller 304. The water heater 307 may be 24V and super insulated. The temperature of the water within the water heater 307 can be read by the temperature sensor and used to determine whether the water temperature is acceptable (i.e. to prevent overheating and / or to alter the priority of water heating within the control logic). The water heating system may comprise dynamic immersion heater temperature control. The controller may be configured to activate the immersion heater intermittently to maintain a standby temperature. The standby temperature keeps the water at a relatively low temperature to limit the heat loss from the immersion vessel. The standby temperature may be determined by a user. The controller may be connected to an operating system which determines the standby temperature. The standby temperature may be determined by the current water temperature and external temperature (temperature outside the cabin). There may be a temperature sensor configured to detect external temperature. The temperature sensor may be located on the outside of the cabin. The operating system may be connected to a wireless network wherein it can obtain the weather forecast to determine the external temperature. The standby temperature may also be determined by the available solar power and the battery’s state of charge (SoC). For example, if the rate of generated solar power and the battery’s SoC are both low, the standby temperature may be allocated to the lower end of the range of standby temperatures. The water within the water heater 307 may be kept at a standby temperature between 10°C, 15°C, 20°C, and 30°C, 40°C, or 50°C. The water within the water heater 307 may be kept at a temperature of 10°C, 30°C, or 40°C. The water within the water heater 307 may be kept at a temperature between 35°C and 45°C. The water within the water heater 307 may be kept at an approximate temperature of 40°C. The controller may also be configured to activate the immersion heater 307 periodically to heat the water to at least 65°C for the purpose of eliminating legionella. The immersion heater 307 may configured to heat up to 65°C once every predetermined period of time. The predetermined time period which the immersion heater 307 may be configured to heat up to at least 65°C may be of the order of 6 hours. The immersion heater 307 may configured to heat up to 65°C at least once in a predetermined time period between 3 hours, 6 hours, or 9 hours and 12 hours, 28 hours, 24 hours, or 30 hours. The predetermined time period may be altered remotely. Alternatively, it may be altered by a controls panel within the cabin. The dynamic immersion heater temperature controller may comprise intermittently heating the water to maintain a standby temperature as described above and once a within a predetermined time period heating the water to at least 65°C. The dynamic immersion heater controller may comprise three modes of operation: • Intermittently heating the water to a standby temperature as described above • Heating the water to at least 65°C once in a predetermined time period • Not heating the water (during prolonged periods of no occupancy e.g. weekends) Alternatively, the water heater may be heated to at least 50°C once in a predetermined time period for a corresponding predetermined period of time for the purpose of eliminating legionella. For example, the water may be heated once in a predetermined time period to 50°C for a period or two hours, or 60°C for a period of five minutes. The lower the temperature, the longer the temperature must be maintained to eliminate legionella. A temperature of at least 65°C does not need to be maintained for a period of time, as legionella would be instantly eliminated. The immersion heater 307 has the advantage that it avoids any costs on load from an inverter present in a typical hotwash system. The water system may further comprises an ultraviolet light in connection with the controller 304. The controller may control the decontamination of the water by the UV light. The controller may decontaminate the water by heating the water to at least 65°C or by activating the UV light. Alternative, the UV light may be used in conjunction with heating the water to at least 65°C. The UV light is position in flow series before the water tank. There may be a flow sensor to detect when there is water flowing within the water system. The UV light may be activated when water is flowing, the UV light may also be intermittently activated at routine intervals when the water is not flowing. When the flow sensor detects no flow of water though the system for a prolonged period of time, e.g., thirty minutes, the controller will activate the UV light at selected intervals. Intermittent activation of the UV light when the water is not flowing ensures the system remains sterile during periods of non-use. This is particularly beneficial in a water system used in a welfare cabin, where the periods in which there is no water flow far exceed the periods where water is flowing. The UV light may be activated at predetermined intervals for the duration of a period in which water is not flowing through the system. The interval in this example is thirty minutes but could be longer or shorter. The intermittent UV light activation will thus prevent any microbes passing to the accumulator. This mode of operation is also energy efficient, i.e. reducing use of the UV light to the minimum amount needed for safe ongoing use of the system. Occupancy monitors may be used to power down the immersion heater when not in use e.g. evenings and weekends. The system may detect whether a user (e.g. a person) is inside the cabin. For example, the cabin may comprise at least one infra-red sensor. Each toilet compartment of the cabin may comprise an occupancy sensor. If a user is not within the cabin, then the water heater may be deactivated to save energy. The heater may be deactivated after a predetermined period of time. For example, the heater may be deactivated when in a predetermined period of time between 60 minutes, 120 minutes, 180 minutes and 4 hours, 12 hours, or 24 hours. When a user enters the cabin, the heater may be re-activated automatically. Alternatively, the water heater may be activate or deactivated remotely or on a control panel within the cabin based on the schedule of use. For example, if no use is scheduled for the next seven days, the water heater may be deactivated for this period of time. Frost protection heater The frost protection heater may comprise a 24V micro heater. The frost protection heater may comprise an ion heater. The toilets comprises part of a freshwater system with pumps, filters, taps and piping. All components of the freshwater system are susceptible to frost damaged. The freshwater system may comprise frost protection. The freshwater system may be warmed by heat loss from the immersion heater. The freshwater system may be warmed by the frost protection heater in sub-zero temperatures to prevent water from freezing. Where the cabin comprises two or more toilet compartments, each toilet compartment comprising a sink, the sinks of each toilet compartment may be within a cluster. The sink of each compartment may share an internal wall with one or more of the other sinks from one or more of the other compartments. The sinks of the compartments are located on an internal wall of the cabin such that the water pipes connected to said sinks are located within an internal space of the cabin. For example, Figure 2 shows the four toilet compartments form an internal corner wherein all the sinks are located. The water pipes connected to the sinks are therefore located internally within the cabin. The sinks of the compartments are clustered together and the water pipes are located within in the internal space of the cabin. As shown in Figure 1, in addition to the four toilet compartments forming an internal corner, the sinks located in the two adjected toilets have sinks adjacent one another sharing an internal wall. The sinks of the compartments are clustered in at least groups of twos and the water pipes connected to the sinks are located within in the internal space of the cabin. Where possible all the sinks of the cabin are clustered together, such as in Figure 2. Where the cabin comprises two or more compartments, each comprising a sink, but it is not possible to cluster all sinks of the cabins, the sinks of the cabins are clustered in at least groups of two, as shown in Figure 1. Sinks may be clustered in twos, threes or fours. The clustered sinks create a sink pod. The sink pod houses the water pipes connected to the sinks. The sink pod may be insulated. The freshwater system may be predominantly contained under an insulated sink pod. The freshwater system may be contained under one or a plurality of insulated sink pods. The freshwater system may be warmed by the frost protection heater in sub-zero temperatures to prevent water from freezing. As the freshwater system is kept in an internal space a minimum amount of power is needed to warm the system when required such that it does not reach freezing temperatures. The water tank may be super lagged. The piping connected to the water tank may be super lagged. All pipes within the water system may be super lagged. The immersion water tank may comprise an insulation jacket. Alternatively, if there is insufficient power available to operate the frost protection heater, water from the system may be evacuated. Water from the water system may be dumped to prevent freezing whilst within the system and causing damage to the system. The controller 304 may be configured to prevent frost damage, e.g. by monitoring water temperature against a minimum threshold temperature (i.e. above freezing) and using a small amount of power to maintain a temperature within the water system. Controller The electrical system 300 may be operatively connected to a remote control / computing device. The remote device may comprise one or more of: a mobile phone; a laptop; a tablet computer; remote server etc. The system may communicate to the device via any suitable means, including a LAN (e.g. Wifi, Bluetooth (RTM)) or WAN (e.g. the Internet). The system may send notifications or data to the device. The remote device may comprise an app or other suitable software to view the data or notifications thereon. The controller may be operated remotely. The remote device may be configured to issue one or more command to the system, for example: • To activate / deactivate the inverter and / or water heater. • To activate / deactivate one or more appliance, • To activate / deactivate any of the components of the electrical system 300 • Any of the components described herein The remote device may be used to set and / or modify one or more parameter / threshold (i.e. setting) on the system. The parameter / threshold may comprise one or more of: • The time period the fan heater 305 may be operate for • The re-activation time period for the fan heater 305 • The time period for heating the immersion heater to at least 65°C. • Energy control • Any other parameter / threshold described herein The cabin may comprise a communication interface for operative communication with a remote device, the controller configured to receive commands from the remote device to allow modification of one or more operating parameter of the cabin. A similar control unit may be provided on or within the cabin itself to allow modification, notification or command issuance as described with reference to the remote device. The control unit may comprise a display and / or input controls (e.g. a touch screen). The controller may comprise maximum power point tracking. The electrical system may comprise the ability to update settings with regards to historical usage and forecast solar gains as described in UK patent 2587850. The electrical system may comprise telemetry to provide owners / users with feedback of all levels of tanks, battery level, usage figures etc, as described in UK patent 2587850. If state of charge on battery is too low, air heating and water heating are abandoned. Electric power priority is the pump for cold water and grey water, UV filter and frost protection (not hot water or air heating).

Claims

1. A self-contained water closet cabin comprising:a renewable energy generator;and an electrical system having an energy store arranged to be charged by the renewable energy generator;a toilet;an air heater located within a first proximity of the toilet so as to deposit air towards an occupant seated on the toilet;a controller configured to control operation of the heater;and a control signal input means for activating the heater, said control signal input means comprising a sensor within a second proximity of the toilet such that the heater is only activatable by a user within the second proximity indicative of when an occupant of the cabin is seated on the toilet.

2. The water closet cabin of claim 1, wherein the air heater is located above the toilet and configured to deposit warm air downwardly towards an occupant when seated on the toilet.

3. The water closet cabin of any preceding claim, wherein the control signal input means comprises a button.

4. The water closet cabin of claim 3, wherein the button is located out of reach of an occupant when not seated on the toilet.

5. The water closet cabin of claims 1 and 2, wherein the control signal input means comprises a proximity sensor.

6. The water closet cabin of claims 1 and 2, wherein the control signal input means comprises a pressure sensor.

7. The water closet cabin of claims 5 or 6, wherein the control signal input activates and de-activates the heater when an occupant of the cabin is no longer seated on the toilet.

8. The water closet cabin of claims 3 and 4, wherein the control signal input means further comprises a proximity or pressure sensor, such that the heater is activated by the button and deactivated by the sensor when the user is no longer seated.

9. The water closet cabin of any preceding claim, wherein the controller activates the heater for a predetermined duration.0? 12 2410. The water closet cabin of claim 8, wherein the predetermined duration is 180s.

11. The water closet cabin of claims 8 or 9, wherein the control input means 5 cannot re-activate the heater until the predetermined duration has expired.

12. The water closed cabin of claims 1 to 9, further comprising an occupancy sensor wherein the control input cannot re-activate the heater during a single occupancy.io13. The water closet cabin of claims 1 to 9, further comprising an external door and an actuation sensor for sensing when the external door is opened and closed; wherein the control input cannot re-activate the heater until the external door has been opened and closed.1514. The water closet cabin of any preceding claim, wherein the heater comprises three power settings and three fan speeds.

15. The water closet cabin of any of the preceding claims, wherein the air 20 heater, renewable energy generator, and the electrical system having anenergy store are connected on a DC circuit.

16. The water closet cabin of any of the preceding claims, further comprising a tank for holding water, a water heater for heating the water within the tank, 25 a temperature sensor for measuring the temperature of the water within thetank, a controller configured to control the temperature of the, the water heater being activated by the controller once in a predetermined time period to heat the water within the water tank to at least 65°C.

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